This invention relates to a reciprocating piston fluid powered motor.
Heretofore, motors of this type have included a large cylindrical bore with a piston reciprocable therein responsive to directed air flow. Air flow has been directed by a valve which includes a spool having circumferential O-rings which fit in the bore of a valve housing. Shifting of the spool valve in response to the position of the piston in one direction causes redirection of pressurized inlet air to a port which causes shifting of the piston in the opposite direction. Exhausting of the motors of this type occurs at a port open to atmosphere.
Oftentimes, contamination, resulting from hydrocarbons in the pressure line from a vehicle engine to the fluid powered motor, will fill the clearance gap around the valve spool between the O-rings within the motor valve housing and resist or prevent movement of the valve spool. Also, the O-rings tend to wear, swell, and stick as a result of the contamination which may include a varnish-like substance which results from engine hydrocarbons. The clearance gap also permits leakage of the varnish substance into the motor valve to cause sticking of the valve spool and ultimately inoperability of the motor.